In a relationship, keep to the commitments you have made to one another. If doing so doesn't make you happy, then have open communication with your partner about whether the terms of the relationship need to be renegotiated or, sadly, whether the relationship itself may have reached the end of its natural life.
With someone with whom you are not in a committed relationship, interact with one another with a view that each of you are created in the image of God. Or, if religious metaphors don't work for you, interact with one another with a view that each of you are deserving of dignity and respect.
The specifics about how this all relates to sexuality will vary. One size doesn't fit all.